JPH039316B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a glow plug energization control method for a diesel engine, and in particular to a method for controlling energization of a glow plug in a diesel engine, which is suitable for use in an automobile diesel engine equipped with an intake throttle valve and an electronically controlled fuel injection device. This invention relates to an improvement in a glow plug energization control method for a diesel engine, which reduces idling vibration by throttling the intake air with an intake throttle valve when the engine is in a high state, and also controls the energization state of the glow plug according to the engine operating state.

Generally, it is known that in a diesel engine, if an intake throttle valve is disposed in the intake passage of the engine and the intake throttle valve throttles the intake air during idling, it is possible to reduce idling vibration and noise.

However, when the intake throttle amount by the intake throttle valve becomes large, the ignitability of the fuel deteriorates and misfires occur. Therefore, there have been problems such as generation of white smoke, engine vibration due to misfire, and deterioration of fuel efficiency.

On the other hand, in recent years, in order to improve the startability of a diesel engine and the idling stability immediately after starting, for example, both a large current and a small current are passed through the glow plug from the time the ignition switch is turned on until the starter is turned off. When the starter turns off, stop applying the large current, and after the starter turns on,
After a predetermined period of time that varies depending on the engine coolant temperature, the small current is also stopped.
A method of controlling energization of a glow plug for a diesel engine has been considered.

However, in the past, the glow plug energization control as described above was performed only at and immediately after starting the engine, and no control was performed in connection with the amount of intake throttle.

The present invention has been made to solve the above-mentioned conventional problems, and even if the amount of intake throttling becomes large, misfire does not occur, and therefore, white smoke and engine vibration due to misfire are prevented, and fuel efficiency is improved. An object of the present invention is to provide a glow plug energization control method for a diesel engine that can prevent the deterioration of the glow plug.

The present invention provides glow plug energization control for a diesel engine that reduces idling vibration by throttling the intake air with an intake throttle valve when idling vibration is large, and also controls the energization state of the glow plug according to the engine operating state. In the method, the first
As shown in the figure, the above object is achieved by energizing the glow plug when the amount of intake throttle by the intake throttle valve is large during idling.

Also, when the intake pipe pressure is less than a predetermined value during the idle time, a small current is applied to the glow plug to prevent overheating of the engine combustion chamber and the glow plug, and to prevent reliability from being impaired. This is what I did.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an electronic control device for an automobile diesel engine, in which a method for controlling energization of a diesel engine glow plug according to the present invention is adopted, will be described in detail with reference to the drawings.

In this embodiment, as shown in FIG. 2, the main intake throttle is arranged in a main intake passage 12 of a diesel engine 10 and rotates in conjunction with, for example, an accelerator pedal 14 operated by a driver. valve 16;
A sub-intake passage 1 that bypasses the main intake passage 12
8 is a sub-intake throttle valve 20 for reducing idle vibration by throttling intake air during idle.
, a drive shaft 24 that rotates in conjunction with the rotation of the output shaft of the diesel engine 10, and a feed pump 26 for pumping fuel that is fixed to the drive shaft 24 (Fig. 2 shows a state rotated by 90 degrees). ), the fuel pressure adjustment valve 28 for adjusting the fuel supply pressure, and the time required for the drive shaft 24 to rotate by a predetermined crank angle are measured from the rotational displacement of the gear 30 fixed to the drive shaft 24. diesel engine 1
A rotation speed sensor 32 made of, for example, an electromagnetic pickup for detecting the rotation speed of 0, a roller ring 34 for controlling fuel injection timing, and a timer piston 3 for driving the roller ring 34.
6. a timing control valve 38 for controlling the position of the timer piston 36, the timer piston 3;
6, a spill ring 42 for controlling the fuel injection amount, and a plunger 44 for driving the spill ring 42.
a, a spill actuator 44 consisting of a compression spring 44b, a coil 44c and a coil case 44d;
A spill position sensor 4 made of, for example, a variable inductance sensor for detecting the position of the spill ring 42 from the displacement of the plunger 44a.
6. Fuel cut solenoid (hereinafter referred to as FCV) for cutting fuel when the engine is stopped 4
8. A fuel injection pump 22 having a plunger 50 and a delivery valve 52;
an injection nozzle 54 for injecting fuel discharged from the second delivery valve 52 into the auxiliary fuel chamber of the diesel engine 10; and an intake pipe 56.
An intake pressure sensor 58 for detecting the pressure of intake air taken in through the engine, an intake air temperature sensor 60 for similarly detecting the temperature of the intake air, and an intake temperature sensor 60 disposed in the cylinder block 10a of the diesel engine 10. A cooling water temperature sensor 62 for detecting the engine cooling water temperature, an accelerator sensor 66 for detecting the depression angle of the accelerator pedal 14 (hereinafter referred to as accelerator opening degree), and the engine combustion chamber 10b are heated to ignite. Both a large current and a small current are energized to the glow plug 67 for increasing the performance, and from when an ignition switch (not shown) is turned on until a starter switch (not shown) is turned off. After the starter switch is turned off, the large current is stopped, and after the starter switch is turned on, the small current is also stopped after a predetermined period of time depending on the engine coolant temperature has passed since the starter switch is turned on. Determine the target injection timing and calculated injection amount based on the engine load detected from the output of the accelerator sensor 66, the engine rotation speed detected from the output of the rotation speed sensor 32, the engine coolant temperature detected from the output of the coolant temperature sensor 62, etc., The timing control valve 38 and the spill actuator 44 are controlled so that the calculated injection amount of fuel is injected from the fuel injection pump 22 at the target injection timing.
In the electronic control device for the automobile diesel engine 10, which is equipped with an electronic control unit (hereinafter referred to as ECU) 68 for controlling the sub-intake throttle valve 20, a negative pressure switching valve is provided. 10 and a diaphragm device 72,
In the ECU 68, idle rotation fluctuation is detected from the output of the rotation speed sensor 32, and when the idle rotation fluctuation amount exceeds a set value, the auxiliary intake throttle valve 20 is controlled in the closing direction, and When the rotational fluctuation amount falls below a set value, the auxiliary intake throttle valve 20 is controlled in the opening direction, and when the intake pipe pressure falls below a predetermined value during idling,
A small current is passed through the glow plug 67 to raise the temperature of the engine combustion chamber 10b.

In the figure, 35 is a cam plate, and 43 is a tension spring.

The ECU 68, as shown in detail in FIG.
A central processing unit (hereinafter referred to as
(referred to as CPU) 69, the output of the cooling water temperature sensor 62 which is input via a buffer 70, and the intake temperature sensor 60 which is input via a buffer 72.
output, the output of the intake pressure sensor 58 which is input via a buffer 74, the output of the accelerator sensor 66 which is input via a buffer 76, and the sensor drive frequency signal of the sensor drive circuit 78 output. The timer position sensor 40 is driven by the output of the spill position sensor 46 inputted via the detection circuit 80 and the sensor drive frequency signal outputted from the sensor drive circuit 82 and inputted via the sensor signal detection circuit 84. A multiplexer 86 for sequentially taking in the output etc., an analog-to-digital converter (hereinafter referred to as an A/D converter) 88 for converting the analog signal output from the multiplexer 86 into a digital signal, and the A/D converter 88 for converting the analog signal output from the multiplexer 86 into a digital signal.
An input/output port 90 for inputting the output of the D converter 88 into the CPU 69, an input/output port 96 for inputting the output of the starter switch 92, etc. input via the buffer 94, and a waveform of the output of the rotational speed sensor 32. A waveform shaping circuit 98 for shaping and inputting it to the CPU 69, and a clock generation circuit 102.
and a backup random access memory (hereinafter referred to as
Random access memory (hereinafter referred to as RAM) 104 including backup RAM (hereinafter referred to as RAM)
, a read-only memory (hereinafter referred to as ROM) 106 for storing control programs and various data, etc., and duty control for the negative pressure switching valve 70 via a drive circuit 110 according to the calculation results in the CPU 69. An output port 108 for outputting a signal; a glow sub-relay 114 for passing a small current through the glow plug 67; and a glow main for passing a large current through the glow plug 67, also in accordance with the calculation result in the CPU 69. Drive circuit 1 for driving relay 116
12, a voltage detection circuit 120 for detecting the voltage across the sensing resistor 118 inserted in series in the current supply circuit to the glow plug 67, and feeding it back to the drive circuit 112; and a calculation result in the CPU 69 as well. , a drive circuit 122 for driving the timing control valve 38, a drive circuit 124 for driving the FCV 48, and a digital-analog converter (hereinafter referred to as D/A) according to the calculation result in the CPU 69. A servo amplifier 126 and a drive circuit 128 for driving the spill actuator 44 according to the deviation between the output of the CPU 69 and the output of the spill position sensor 46, which are converted into an analog signal by an analog signal (referred to as an A converter) 124; It consists of In FIG. 3, 130 is a glow plug resistor for limiting the current flowing to the glow plug 67 when a small current is applied.

The action will be explained below.

Intake throttle control and glow plug energization control in this embodiment are executed according to a crank angle interrupt routine as shown in FIG. That is, the above
The CPU 69 of the ECU 68 enters step 1010 at every predetermined crank angle to calculate the engine rotational speed NE. Next, the process proceeds to step 1020, where it is determined whether or not the engine is idling because, for example, the accelerator pedal 14 is fully closed and the engine rotational speed is below a predetermined value. If the determination result is positive, that is, if the engine is idling, the process proceeds to step 1030, and it is determined whether afterglow is turned off because, for example, the glow sub-relay 114 was turned off during fast idling immediately after the engine was started. Determine whether or not. If the determination result is negative, that is, if fast idling is in progress, the process proceeds to step 1040, where a predetermined value, for example 30%, is input to the duty control signal D for driving the negative pressure switching valve 70. , exit this routine. These steps 1030 and 1040 maintain the opening degree of the auxiliary intake throttle valve 20 when the glow sub-relay 114 is on during afterglow, that is, during fast idle, and also maintain the opening degree of the sub-intake throttle valve 20 according to the intake throttle amount according to the present invention. Glow sub relay 114 is activated by glow plug energization control.
This is to prevent it from being turned off.

If the determination result in step 1030 is positive, that is, afterglow is already turned off, the process proceeds to step 1050, where the average engine speed determined by averaging the engine speeds at idle is calculated. Find the difference |△Ni| between the speed and the current engine rotation speed NE. Then,
Proceeding to step 1060, the average value of the rotational speed difference |ΔNi| of 20 times is determined, for example, using the following equation.

｜△N｜= ₂₀ 〓 ⁱ⁼¹ ｜△Ni｜ …(1) Here, in step 1060, the rotational speed difference |
The average value |△N| of Ni| is determined because it is dangerous to change the opening degree of the auxiliary intake throttle valve 20 based on one data set.

After step 1060, the process proceeds to step 1070, where the average rotational speed difference |△N| is determined as a judgment value, e.g.
Determine whether the speed exceeds 50 rpm. If the determination result is positive, that is, if the idle rotation fluctuation is large, the process advances to step 1080 and the duty control signal D is output to the negative pressure switching valve 70.
By reducing , for example, by a predetermined value of 3%, the auxiliary intake throttle valve 20 is controlled in the closing direction. On the other hand, if the judgment result in step 1070 is negative, the process proceeds to step 1090, where the average rotational speed difference |△N| is the judgment value, e.g.
Determine whether the speed is less than 30 rpm.

Step 1090 or step 1020
If the determination result is negative, step 109
5, the current value is used as the duty control signal D, and this routine ends.

On the other hand, if the determination result in step 1090 is positive, that is, it is determined that the idle speed fluctuation is extremely small and that there is room to open the auxiliary intake throttle valve 20 and improve other engine operating performance such as fuel efficiency. If so, proceed to step 1100, and add, for example, a predetermined value of 3% to the duty control signal D output to the negative pressure switching valve 70.
The sub-intake throttle valve 20 is controlled in the opening direction.

After completing step 1080 or 1100, the process proceeds to step 1110, where the relationship between the engine coolant temperature THW and the upper limit value Dmax and lower limit value Dmin of the duty control signal D, as shown in FIG. 5, is stored in advance in the ROM 106. From the table showing the upper limit value Dmax and
Find Dmin. Next, the process proceeds to step 1120, where the duty control signal D obtained in the previous step 1080 or 1100 reaches its upper limit value Dmax.
Determine whether or not it exceeds. If the determination result is positive, the process proceeds to step 1130, where the duty control signal D is set to the upper limit value Dmax. On the other hand, if the determination result in step 1120 is negative, the process proceeds to step 1140, where it is determined whether duty control signal D is less than its lower limit value Dmin. If the determination result is positive, the process proceeds to step 1150, where the lower limit value Dmin is set as the duty control signal D.

Here, the duty control signal D has an upper limit value.
The reason why Dmax and lower limit value Dmin are set is because of feedback control according to fluctuations in idle speed. Especially when the engine is cold, the amount of throttling becomes too large, causing white smoke and deteriorating fuel efficiency and exhaust gas purification performance. This is to prevent the throttle amount from becoming too small and to prevent the failsafe from becoming ineffective when the fuel injection amount increases due to an abnormality in the ECU 68 or the fuel injection pump 22. or,
As is clear from Figure 5, the engine cooling water temperature
The lower the THW, the lower the upper limit Dmax and the lower limit
The reason why Dmin is set high is to ensure smooth fast idle immediately after engine startup, improve ignition performance, and prevent the generation of white smoke.

After the above step 1130 or 1150 is completed, or if the judgment result in the above step 1140 is negative, the process proceeds to step 1160 and the duty control signal D is stored in the RAM 104.

The process then proceeds to step 1170, where the intake pipe pressure is
It is determined whether Pm is less than a predetermined value, for example -200 mmHg. If the determination result is positive, that is, if it is determined that the intake throttle amount by the sub-intake throttle valve 20 is large, the process proceeds to step 1180, where the glow sub-relay 114 is turned on to A small current is applied to the glow plug 67, and this routine ends.

On the other hand, if the determination result in step 1170 is negative, the process advances to step 1190.
The glow sub-relay 114 is turned off and this routine ends.

In this embodiment, when the intake pipe pressure is less than a predetermined value during idling, a small current is applied to the glow plug 67, so there is no fear that the glow plug 67 will be overheated, and the engine combustion chamber 10b can be effectively heated. Note that the method of supplying electricity to the glow plug 67 is not limited to this. For example, when the intake pipe pressure is less than a predetermined value during idling, the glow main relay 116 is turned on for a predetermined time, and a large current is applied to the glow plug 67 for a predetermined time. It is also possible to increase responsiveness by energizing. Further, by proportionally controlling the amount of electricity supplied to the glow plug 67 according to the intake pipe pressure, it is also possible to perform more appropriate heating.

In the above embodiment, the sub-intake throttle valve 20
Although the opening degree of the auxiliary intake throttle valve is linearly controlled using the duty control signal D, the method of controlling the opening degree of the auxiliary intake throttle valve is not limited to this, and for example, it is also possible to configure the opening degree to be controlled in multiple stages. be.

Furthermore, in the embodiment described above, the opening degree of the auxiliary intake throttle valve 20 was controlled in accordance with the idle rotation fluctuation, but the method of controlling the opening degree of the intake throttle valve is not limited to this, for example, It is also possible to detect idle vibration and control the opening degree of the sub-intake throttle valve or other intake throttle valve according to the idle vibration level.

In the above embodiments, the present invention was applied to an automobile diesel engine equipped with an electronically controlled fuel injection device, but the scope of application of the present invention is not limited thereto, and is applied to a general automobile diesel engine equipped with another fuel injection device. It is clear that the same applies to diesel engines.

As explained above, according to the present invention, the ignitability of fuel is improved even when the amount of intake throttle is large, so that white smoke and engine vibration due to misfire are prevented, and fuel efficiency is deteriorated. can be prevented. Therefore, for an engine with large idling vibrations and rotational fluctuations, the intake air can be throttled more strongly than in the misfire occurrence region, and has excellent effects such as being able to effectively reduce idling vibrations and rotational fluctuations.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the gist of the glow plug energization control method for a diesel engine according to the present invention;
FIG. 2 is a cross-sectional view, partially including a block diagram, showing the structure of an electronic control device for an automotive diesel engine in which the diesel engine glow plug energization control method according to the present invention is adopted;
FIG. 4 is a block diagram showing the configuration of the electronic control unit used in the embodiment, FIG. Figure 5 shows the steps used in the routine.
FIG. 2 is a diagram illustrating an example of the relationship between engine cooling water temperature and the maximum and minimum values of the duty control signal of the negative pressure switching valve. 10... Diesel engine, 14... Accelerator pedal, 16... Main intake throttle valve, 20... Sub-intake throttle valve, 22... Fuel injection pump, 32... Rotational speed sensor, 66... Accelerator sensor, 67...
...Glow plug, 68...Electronic control unit (ECU), 69...Central processing unit (CPU), 7
0...Negative pressure switching valve, 72...Diaphragm device,
108... Output port, 110, 112... Drive circuit, 114... Glow sub relay, 116...
Glow main relay, 118...sensing register, 120...voltage detection circuit, 130...glow plug resistor.

Claims (1)

[Claims] 1. When the idle vibration is large, the intake air is throttled by an intake throttle valve to reduce the idle vibration,
In the glow plug energization control method for a diesel engine, which controls the energization state of the glow plug according to the engine operating state, when the intake throttle amount by the intake throttle valve is large during idling, the glow plug is energized. A method for controlling energization of a glow plug in a diesel engine, characterized in that: 2. The glow plug energization control method for a diesel engine according to claim 1, wherein a small current is passed through the glow plug when the intake pipe pressure is less than a predetermined value during the idle time.